This doweling jig uses left and right hand threads to keep the center block drill guide centered on whatever board you clamp it to. It has drill guides for 1/4" and 3/8" drill bits. It uses hardware available in most hardware stores. All printed parts which require threads for assembly are printed with the threads.

Note: If you have difficulty downloading or printing files, leave me a message. One person was unable to download a file until I re-posted it from a different source. I have been posting files after positioning on build plate and exporting with Cura. I notice that this increases the size of the STL file considerably. I can upload new files if necessary that have been positioned in FreeCAD and which are smaller than previously posted files. Any future projects will not use the Cura export but will be positioned from FreeCAD before producing the STL file. Sorry for any inconvenience I may have caused.